Combinations are known in which a mechanical locking system, operated by mechanical means, cooperates with a mechanical locking system operated by electromagnetic means. Conventional practice employs the mechanical means for opening a closure in situ, e.g. by means of a door knob, door latch, key, etc., while the electromagnetic means is used for operating the same closure from a distance.
For example, the independent positioning of the place to actuate or manipulate the electromagnetic means permits central monitoring of remote closure systems in part. This monitoring can take place in a fully automatic time-dependent manner by the action of an operator, by imposing predetermined states, etc.
It is generally an additional closure means, i.e. additional to the mechanical means, which is used in a conjunctive or disjunctive manner. These conjunctive and disjunctive possibilities extend the use of closure systems, particularly from an organizational standpoint. For example, this is shown by the truth table to be used in this connection, e.g., relative to a door:
______________________________________ Mechanical Electromagnetic ______________________________________ 0 0 Door open for everyone 1 0 Access only to key holders 0 1 Access allowed from control center 1 1 Control center allows access for certain key holders. ______________________________________
The organizational possibilities are extended by the two alternatives of key or control center. Security is increased by the conjunctive possibility of key and control center.
The advantages of such combined closure systems are, for example, described and used in DOS No. 2,325,566. The mechanical means for actuating the closure, specifically a door closure, are turning handles or knobs arranged on the door for sliding a bolt. The electromagnetic means actuate an additional bolt, which locks or releases as a function of the main bolt position. A security cylinder is provided for the actuation or release of the electromagnetically operated additional bolt, with the security cylinder being associated in an interrogating device. The electromagnetic part is housed in the door frame, as is the safety cylinder releasing the electromagnetic means. The security cylinder only operates the electromagnetic locking system with the aid of a specially machined serrated or notched bit key, the back of which contains the information for the reading device. Electromagnetic release can also take place disjunctively, i.e. in a key or control center form.
Page 158 of the Journal "Baubeschlag Magazin" No. 10/80, October 1980, describes another solution for the combined closure system. The main bolt is blocked by an additional bolt operable by electromagnetic means. The additional mechanical locking system manipulated by a safety cylinder and using a key, is housed together with the electromagnetic means in the door lock box, i.e. not separately in the door and the frame. The lock bolt is blocked in the rear bolt part and not in the front bolt part.
A special construction of the closure means is required for blocking a bolt acting, e.g., between the door and the door frame, either by means of a device in the frame or a device in the door. To subsequently provide an electromagnetic additional closure means in an existing closure of a random type, but particularly on doors, it is necessary to carry out modifications in the mechanical part of the lock. This preferably involves the replacement of an existing lock by a lock for the electromagnetic additional locking system, or which has already been manufactured with this system.
This replacement naturally involves high costs, because otherwise intact locking mechanisms must be completely replaced. This often involves additional modification expenditure on the existing door or door frame. Thus, the additional security is often not utilized, particularly if it is necessary to modify a large number of closure systems.